1. Field of the Invention
The present invention relates to a memory system, and more particularly, to a termination providing apparatus mounted on a memory module or a socket and a memory system using the apparatus.
2. Description of the Related Art
As demands for a memory system offering a high speed data rate in excess of 800 Mbps increase, there has been suggested a memory system using short loop through (SLT) technology as shown in FIG. 1, instead of a stub bus technology which has been used but has a speed limitation.
Referring to FIG. 1, in a memory system using SLT technology, data signals are output from a memory controller 11, input to an ith pin of a first memory module 17 through a bus line 12a and a first socket 13, and applied to a specific pin of a dynamic random access memory (DRAM). After being applied to the specific pin of the DRAM, the data signals are output to a bus line 12b on a mother board through a jth pin of the first memory module 17 and the first socket 13. The data signals having passed through the bus line 12b, a second socket 15, and a second memory module 19 in the same way as above are finally terminated at a termination voltage level Vt through a termination resistor Rt.
In the memory system using SLT technology, since twice as many pins as the number of signals should be mounted on a socket and a memory module, the number of pins disadvantageously increases. The increase in the number of pins reduces a pin pitch, thereby raising the cost of the socket. In general, when the pin pitch of the socket is reduced from 1.0 mm to 0.9 mm, the cost of the socket is at least doubled. Further, the increment in the number of pins also increases an insertion force, thereby worsening a module assembly environment.
In addition, as shown in FIG. 2, when only one module 17 is required in a memory system including at least two sockets 13 and 15, all signals are connected through the module. Thus, a continuity module 29 on which no DRAM is mounted is required, thereby raising the cost of the memory system.